Breastfeeding is often described as “natural,” but that doesn’t mean it always feels intuitive. One of the biggest sources of anxiety for new parents is the question: Am I making enough?
To answer that with confidence, we need to look beyond the pump output or the clock. We need to understand the biology of milk production as a living, responsive system—not a gas tank that simply fills up and empties.
The Hormone Dance: Prolactin and Oxytocin
Your milk supply is driven by a feedback loop between your body and your baby. It relies primarily on two hormones:
- Prolactin: The “production” hormone. When your baby nurses, prolactin levels spike, signaling your body to produce milk for the next feed.
- Oxytocin: The “delivery” hormone. This triggers the let-down reflex, squeezing the milk out of the alveoli and into the ducts so the baby can drink.
Because this system relies on feedback, fluctuations are normal. Stress, fatigue, and hydration can affect let-down (oxytocin), even if your production capability (prolactin) is perfectly fine.
The Reality of the Newborn Stomach
Many parents worry in the first few days because they aren’t seeing ounces of white milk. This is by design. Your body produces colostrum first—a nutrient-dense, concentrated “liquid gold.”
You produce colostrum in small amounts because your baby’s stomach is tiny:
- Day 1: The baby’s stomach is the size of a cherry (approx. 5-7ml).
- Day 3: It grows to the size of a walnut (approx. 22-27ml).